The correct expression for Ostwald’s dilution law for a solution of weak electrolyte is

Ostwald's law of dilution relates with the dissociation constant of a weak electrolyte to the degree of dissociation and the concentration of the weak electrolyte.

Consider the following reaction,

                                 $C{H}_{3}COOH\rightleftharpoons C{H}_{3}CO{O}^{-}+H^{+}$

                                    $K_a=\frac{\left[C{H}_{3}CO{O}^{-}\right]\left[H^{+}\right]}{\left[C{H}_{3}COOH\right]}$

                                   $K_a=\frac{\alpha C.\alpha C}{(1-\alpha )C}$

                                   $K_a=\frac{{\alpha }^2}{(1-\alpha )V}$, Where $C=\frac{1}{V}$

Hence, the correct answer is option (A)$K_a=\frac{{\alpha }^2}{(1-\alpha )V}$.